The lengths to which someone with a grudge will go are amazing. I've held a grudge before. There is something satisfying about contemplating revenge when you feel you've been wronged. Revenge can be taken creatively, or in a straightforward fashion. I've read books on revenge. But in the final analysis, I've perpetrated few if any spiteful acts.
Sure, I've had my dark moments. But I think that most sane people realize that thoughts of revenge are nothing more than an unhealthy fixation that drains your time and energy. In a way, they drain your life itself. And so we hopefully stop short of exacting our retribution on whatever unsuspecting target has drawn our ire.
A poker metaphor here is apt, if only to illustrate the practical reason to eschew spite if you can gain the upper hand on your emotions. When you take a particularly bad beat (someone beats you out of a hand you feel you should have won) there is sometimes the feeling that you need to "get" that other person at the poker table. You want to return the favor. And if the urge is strong, and you wallow in your misfortune and/or entertain thoughts of anger, you will, as poker players say, "go on tilt."
When you're on tilt you're neither thinking nor playing clearly. People on tilt are off their game, they're playing poorly because they have lost focus. Something is in the way of their mind.
Life is the same way. When you "go on tilt" in real life, you have lost your general perspective of the world. You have narrowed your focus to the point where you no longer see the bigger picture.
Speaking of that, the Guardian has a bizarre story of a homosexual columnist who is being stalked by a homophobe. The columnist is being harassed in a number of ways through telephone and post. It's an amazing waste of time, and it underscores how much further there is to go in the western world before we can live and let live.